Method for air-bubble texturing endless filament yarn, yarn finishing device and its use

ABSTRACT

A method and machine for treating yarn may include feeding the yarn through both a heat treatment and an air jet texturing nozzle. The texturing nozzle may be supplied with compressed air, producing an air jet with a speed greater than Mach  1  in the yarn channel. The heat treatment may be performed before and/or after feeding the yarn through the texturing nozzle.

TECHNICAL SCOPE

This invention relates to a method of air jet texturing of continuousfilament yarn with an air jet texturing nozzle having a continuous yarnchannel at whose one end the yarn is supplied and at whose other end thetextured yarn is removed, and compressed air is supplied to the yarnchannel in a central section, and in an enlarging acceleration channelthe air blast jet is accelerated to a supersonic speed, and loop yarn isproduced at a high rate of transport of preferably more than 600 m/min,where the air jet texturing zone is bordered by a feeder roll 1 at thebeginning of the air finishing stage and a feeder roll 2 at the end ofthe air finishing stage.

This invention also relates to a yarn finishing machine with a texturingzone consisting of a feeder roll 1 for supplying the yarn, a texturingnozzle and a feeder roll 2 downstream from the texturing nozzle, wherethe texturing nozzle has a continuous yarn channel at whose one end theyarn is supplied and at whose other end the textured yarn is removed,and compressed air is supplied to the yarn channel in a central sectionand an air blast jet at a supersonic speed can be generated in anexpanding acceleration channel.

STATE OF THE ART

This invention is based on air jet texturing according to InternationalPatent WO97/30200. Finishing of continuous filament yarn must fulfillmainly two functions. First, a textile character is to be imparted tothe yarn produced from industrially synthesized filaments, and technicaltextile properties are to be imparted. Secondly, the yarn is to befinished from the standpoint of specific quality features of the endproduct which often cannot be achieved with products manufactured fromnatural fibers. A very important goal with industrially producedfilaments and the yarns and textiles produced from them is to optimizethe processing operation. Optimizing here means maintaining orincreasing certain quality criteria and reducing production costs. It isknown that production costs can be reduced in various ways, The mostobvious way is to increase throughput speed in a given productionfacility. Another possibility involves technical process measures thatneed not necessarily include an increase in throughput speed but insteadensure certain quality criteria even at high yarn throughput speeds.

Especially in the case of continuous filaments, the textile industry isone of the most complex branches of the industry since severalindependent branches of the industry and commerce are involved from theraw material stage to the finished fabric. None of these branches iscompletely autonomous, and instead there is a processing chain where anychange in process in one stage can influence the following stages oreven preceding stages. However, it is still not known whether the finalconsumer will accept or reject the product after changes with respect toquality properties have occurred due to new process techniques. In someproduct sectors, especially in filament spinning mills, yarn finishingthrough yarn finish nozzles is the most important step. The change instructure from smooth yarn to a textured loop yarn is achieved merelythrough mechanical air forces. Air flow in the supersonic range isgenerated, as described in the above-mentioned International Patent WO97/30200. All attempts known so far have shown that the texturing effecthardly changes when using, for example, hot air for the blasting air inthe nozzle. The simplest explanation for this is that hot compressed airexpands suddenly, cooling at the same time. The heating effect of heatedair is mostly lost with this expansion and the corresponding coolingeffect.

Unexamined German Patent No. 2,822,538 describes a method of producingPET carpet yarn. This method is stuffer box crimping which is carriedout as an integrated process within a spin draw texturing process withtransport rates of more than 1800 n/min. In stuffer box crimping,deformation of the yarn is supported chemically in contrast with air jettexturing where air force alone produces the deformation effect.

U.S. Pat. No. 4,040,154 describes another example of stuffer boxcrimping using superheated steam. Stuffer box crimping here takes placewithin the cylindrical channel. The yarn leaves the channel withouttension. This is in contrast with the actual texturing where the tensionproduced in the yarn at the outlet from the nozzle provides a measure ofthe quality of the texturing operation. Texturing was previously oftenunderstood in the most general sense and was not taken as a technicalconcept.

EXPLANATION OF THE INVENTION

The object of the present invention was to optimize the processingoperation in the production of a loop yarn. A portion of the object ofthis method is then in particular to allow higher yarn transport speedswithout any loss of quality..

The method according to this invention is characterized in that the yarnis heated between a first feeder roll and a second feeder roll by anupstream and/or downstream yarn heating device such that both themechanical air effect and the thermal effect take place between thefirst feeder roll and the second feeder roll.

FIG. 2 shows with curve T311 a purely schematic diagram of texturingaccording to the state of the art as stipulated in International PatentWO97/30200. Two main nozzle parameters are emphasized: an opening zoneOe-Z1 and an impinging front diameter DAs starting from a diameter d ofthe nozzle yarn channel. On the other hand, the diagram shows texturingaccording to the teaching of International Patent WO97/30200 with anincreased output at the upper right of the diagram. This shows veryclearly that the values Oe-Z2 and D_(AE) are greater in comparison withthose obtained with nozzle T311. Yarn opening begins before theacceleration channel in the area of compressed air supply P, i.e., inthe cylindrical section. VO is the pre-opening. Mass Vo is preferablygreater than d. The main information from FIG. 1 is the diagramedcomparison of the yarn tension Gsp (cN) according to curve T311 at Mach<2 and a texturing nozzle according to curve S 315 at Mach> 2. The yarntension is given in cN in the verticals of the diagram. The horizontalsshow the production speed Pgeschw in m/min. Curve T311 shows the rapidcollapse in yarn tension at production speeds of 500 m/min. Aboveapproximately 650 m/min, texturing collapsed. In contrast with that, thecurve S 315 shows that the yarn tension is not only much higher but isalmost constant in the range of 400 to 700 m/min, and also drops moreslowly in the higher production range. The increase in Mach number isone of the most important “secrets” for making progress in increasingproduction output according to International Patent WO97/30200. It wascompletely surprising that the increase in production output was notexhausted at all with the special design of the acceleration channel.Two central findings make it possible to open another gate to evenhigher speeds with no loss of quality, namely the additional combinationof:

a higher air pressure, and

a thermal treatment before and/or after texturing.

Although in practice, one cannot speak of strictly separate stages inthe actual sense, such a representation still comes very close to theactual situation. If a production speed of 1200 m/min is assumedaccording to the present invention, then 250 m/min of that is due to theincrease in pressure to 10-12 bar and an additional 200 m/min is due tothe further increase to 12-14 bar (in addition to the effect of heat).According to experiments so far, a further increase in output is readilypossible. With an increase in pressure to more than 8 or 9 bar, thismerely creates the prerequisite for increasing the Mach number. This isespecially effective if the texturing nozzle is designed according tothe teaching of International Patent WO97/30200. It may be assumed thateven greater increases to 1500 m/min or even more are possibleaccordingly. According to experiments so far, there is no upper limit tothe production rates that can be achieved. Furthermore, anotherinteresting observation is that the thermal effect alone either upstreamand/or downstream from the texturing nozzle itself would yield anincrease in output with an old nozzle with Mach< 2. This new inventionhas shown that there are causal relationships between the increase inpressure, Mach number, yarn transport rate and thermal influence. Thestiffness of the individual filaments is reduced with the heat treatmentupstream from texturing. Filaments can bend more easily and with lessenergy when they are warm, which is the main reason for this component.With the heat treatment arranged downstream from texturing, the changein structure that takes place in texturing is more complete. Onepossible explanation for the surprisingly great effect of the thermaltreatment is that with a simultaneous increase in yarn throughput speed,the period of time for possible cooling is also reduced in half Thus,the heat effect is manifested to a greater extent. For especiallyadvantageous embodiments, reference is made to claims 2 through

This invention also concerns a yarn finishing machine and ischaracterized in that a yarn heating device DK1, DK2 is arranged betweentwo feeder rolls. One heating device DK1 may be located downstream fromthe texturing nozzle TD and upstream from the second feeder roll LW2,for example, while the other heating device DK2 may be located upstreamfrom the texturing nozzle TD and downstream from the first feeder rollLW1, for example. This invention also relates to the use of a heattreatment upstream and/or downstream from a texturing nozzle thatproduces an accelerated air flow at supersonic speed, for example morethan Mach 2 in the acceleration channel.

BRIEF DESCRIPTION OF THE INVENTION

The present invention is described in greater detail below on the basisof several embodiments, showing:

FIG. 1: a survey of the new texturing process;

FIG. 2: a comparison of a texturing nozzle with Mach> 2 and a texturingnozzle with Mach< 2;

FIGS. 3a through 3 e: the state of the art with respect to texturing;

FIG. 4: a texturing zone according to this invention;

FIGS. 5a through 5 d: different variants for use of heat treatments;

FIG. 6: possible performance stages through a combination if variousembodiments.

METHODS AND IMPLEMENTATION OF THE INVENTION

Reference is made to FIG. 1, showing a schematic diagram with respect tothe new texturing process. The separate steps of the process are shownin succession from top to bottom. A smooth yarn 100 is conveyed over thefirst feeder roll LW1 at a given transport speed V1 to texturing nozzle101 and through yarn channel 104. Highly compressed, preferably unheatedair is blown at an angle α in the direction of the transport of the yarninto yarn channel 104 through compressed air channels 103 connected to acompressed air source PL. Immediately thereafter, the yarn channel 104opens conically such that a greatly accelerated air flow at a supersonicspeed, preferably at more than Mach 2, is established in conical section102. The shock waves from the supersonic air flow produce the actualtexturing effect. The first section of the air injection zone 105 whereair is blasted into yarn channel 104 up to the first section of theconical enlargement 102 serves to loosen and open the smooth yarn sothat the individual filaments are exposed to the supersonic air flow.Texturing is achieved according to the available air pressure (9 to 12or even 14 bar or more) either within conical section 102 or in theoutlet area. There is a direct proportionality between the Mach numberand texturing. The higher the Mach number, the greater the impingingeffect and the more intense the texturing. Two critical parametersobtained from the production speed:

the desired quality standard, and

flapping, which can lead to a collapse of texturing with a furtherincrease in transport speed.

The following abbreviations are used:

Th. vor.: thermal pretreatment, optionally with heating of the yarn orwith superheated steam,

G. mech.: yarn treatment with the mechanical effect of a compressed airflow (supersonic air flow),

Th. nach.: thermal aftertreatment with superheated steam (possibly onlyheat or only superheated steam),

D: steam

PL: compressed air.

Production speed was successfully increased up to 1500 m/min with anadditional thermal treatment without any collapse of texturing andwithout any flapping, where the limit was determined on the basis of theexisting experimental facility. The best texturing quality was achievedat a production speed of far more than 800 m/min. Surprisingly, theinventors have discovered one or two completely new quality parameters,although the principle defined above (higher Mach number=greaterimpinging=more intense texturing) was confirmed in all the experiments.The parameters discovered include first a heat treatment upstream and/ordownstream from texturing and secondly an increase in Mach number due tothe increase in air pressure and a corresponding design of theacceleration channel. During the heat treatment, the yarn may be heatedto more than 90 degrees Celsius.

a) Thermal Aftertreatment or Relaxation

An Important quality criterion in texturing is evaluated by thoseskilled in the art on the basis of the yarn tension of the yarn exitingfrom the texturing nozzle, which has been acknowledged as a measure ofthe intensity of the texturing effect. The yarn tension of textured yarn106 is established between the texturing nozzle TD and feeder roll LW2.In this range, i.e. between texturing nozzle TD and feeder roll LW2, athermal treatment was performed on the yarn under tensile stress. Theyarn was heated to approximately 180 degrees Celsius. Preliminaryexperiments have already been concluded successfully using both a hotpin or heated rollers and a hot plate (non-contact), with the surprisingresult that the quality limit with respect to transport speed could beincreased massively. At the present time, it is assumed that the thermalaftertreatment described here has a fixative effect and at the same timehas a shrinkage effect on the textured yarn, thereby supporting thetexturing effect.

b) Thermal Pretreatment

It was even more surprising that thermal pretreatment also has apositive effect on the texturing operation. The reason for this successhere might be due to a combination effect of yarn shrinkage and yarnopening that takes place in the section between the point of airinjection into the yarn channel and the first partial segment of conicalwidening in the range of ultrasonic velocity. Since the yarn is heated,its stiffness is reduced, thus improving the prerequisite for loopformation in the texturing process. Here again, experiments have beensuccessfully concluded with both hot plate and hot pin elements as heatsources. The fact that a negative cooling effect due to air expansion inthe texturing nozzle is avoided with thermal pretreatment of the yarnmight also be a supporting factor here, and therefore, texturing of theheated yarn is improved. At very high transport speeds, a portion of theheat remains in the yarn itself up to the area of loop formation.

Using a processing medium D can maximize the effect of the thermaltreatment. An example of a processing medium D is superheated steamsupplied through a channel 114 into a treatment body DK1, DK2. Otherpossible mediums include hot air or some other type of hot gas, forexample. The treatment body DK1, DK2, as shown in FIG. 1, may be aclosed flow-through steam chamber 41 formed as a closed nozzle defininga medium feed channel 41 a with a large cross section. A two-parttreatment body DK1, DK2 approximately symmetrical in both parts andapproximately the same shape in both nozzle halves may be used, as shownin FIG. 1.

If the effect is maximized by a processing medium—whether hot air,superheated steam or some other hot gas—then preferably the additionalthermal process steps are separated locally or are carried out on therunning yarn shortly or directly in succession. The process measures arenot isolated in this way but instead are combined in a shared actionbetween two feeder rolls. This means that the yarn is secured only atthe beginning and at the end, while both the mechanical action of airand the thermal action on the yarn take place between the feeder rolls.The thermal treatment is performed at the tensions produced mechanicallyin the filments or in the yarn by the compressed air.

FIG. 2 gives an overview of yarn tension (Gsp) and production speed. Thelower portion of the figure at the left shows the result obtained with anozzle T311, where the yarn was heat treated with T311+Th. The dash-dotlines T311+Th are only the result of sampling experiments. In the upperpart of the figure, a nozzle S 315 with an acceleration channel forMach> 2 is used. The air pressure used as the basis for texturing is notshown in the two curves. The dash-dot curve S 315+Th shows mainly thegreat effect of the heat treatment. Since a plurality of yarn grades andyarn titers are available, it was impossible to accurately determine thecorresponding relationships. According to experience in textiletechnology, this can be done only in actual production use.

However, FIG. 2 illustrates the steps in increasing production with thevarious combinations. A PA 78151, core 10%, effect 30% and a pressure of9 bar were used as the reference material.

FIGS. 3a through 3 e show the typical solutions according to the stateof the art with various feeder rolls W0.1, W0.2, W1.1, W1.2, W2, W3, W4,WW operating at various speeds, some examples of which are shown in FIG.4. FIG. 3a shows schematically the known individual or parallelprocessing of FOY yarn. FIG. 3b shows parallel processing of FOY and POYyarns. FIG. 3c shows the processing of POY yarn with core yarn andeffect yarn. FIG. 3d shows examples of various embodiments of texturedyarns 106 and FIG. 3e shows a classical texturing nozzle. The texturingnozzle TD shown in FIG. 3e is a T311 nozzle, with smooth yarn 100 beingsubject to compress air PL in the texturing nozzle TD resulting intextured yarn 106.

FIG. 4 shows schematically according to FIG. 3 the use of the newsolution in texturing. In contrast with the diagram in FIG. 1, aso-called hot plate (H.plate) is used for the thermal treatment, i.e., anon-contact heating channel as illustrated in FIGS. 3b and 3 c. Theentire air processing stage is labeled as LvSt in FIG. 4 in a diagramaccording to FIG. 1. FIG. 4 shows a thermal pretreatment 120 as well asa thermal aftertreatment 121, with the most important process dataincluding the air pressure, temperature and yarn speeds. H.plate meanshot plate and H.pin means hot pin. A yarn moistening step HemaJet 123 isarranged upstream from the texturing nozzle 101. Downstream from the airfinishing stage, the yarn is usually drawn or subjected to a drawingoperation by a few percentage points (1-2%). Then the yarn is passedover another heater 122 which may also be a steam chamber. Ifsuperheated steam is used for the thermal treatment at one station, itmay be advisable for economic reasons to also design the other heatingstations to operate with superheated steam. The table shows the yarnspeeds at the feeder rolls (W) indicated as an example.

FIGS. 5a through 5 d illustrate the use of the so-called heated anddriven rollers for thermal treatment with a few possible applications.The temperature shown in the roller indicates whether or not it is aheated position. Accordingly, a hot plate or a through-flow steamchamber may also be used in all embodiments.

FIG. 6 illustrates very roughly in diagram form the increase in speedranges, with the possible increase in production speed for an identicaltexturing quality shown in each case. The blocks shown here representdifferent combinations for the texturing process from bottom to top. Theupper half of the figure shows transparencies according to FIGS. 1, 4and 5, illustrating the increased production achieved, or the productionspeed while maintaining a certain predetermined yarn quality.

Block 500 shows the state of the art with a texturing nozzle T311according to FIG. 3e at 9 bar, 500 m/min.

Block 150 shows a texturing nozzle S 315. Experiments have shown thatblock 150 is also possible with a nozzle T311 with an additional thermalprocess. This is indicated with a dash-dot arrow.

Block 100 also shows a set heater.

Block 250 also shows a thermal aftertreatment (FIG. 5a) at 10-12 bar andwith a hot plate C/E/ATY; SET.

Block 200 also shows a thermal pretreatment (FIG. 5d) at 12-14 bar witha hot plate C/E/ATY; SET.

The increase in production according to blocks 250 and 200 was achievedat a constant quality using only one texturing nozzle, i.e., at morethan Mach 2 in the acceleration channel 104. Block 250 presupposes ahigher pressure and a heat treatment. Block 200 presupposes all theproposed measures. Block 150 may optionally be achieved with a nozzleT311 and thermal treatment.

This invention also relates to the use of at least one or two heattreatments upstream and/or downstream from a texturing nozzle at Mach> 2in the acceleration channel.

What is claimed is:
 1. A method for treating a continuous filament yarn comprising: supplying the yarn in a drawn state to a first feeder roll; supplying the yarn to an air jet texturing nozzle after supplying the yarn to the first feeder roll, wherein the nozzle defines a yarn channel having a substantially conical section; air jet texturing the yarn in the nozzle via compressed air radially entering the yarn channel substantially at an entrance of the conically shaped portion, the air reaching at least supersonic speed in the yarn channel; supplying the yarn to a second feeder roll after air jet texturing the yarn; and heating the yarn between the first feeder roll and the second feeder roll.
 2. The method of claim 1, wherein the heating of the yarn occurs before the air jet texturing.
 3. The method of claim 1, wherein the heating of the yarn occurs after the air jet texturing.
 4. The method of claim 1, wherein the heating of the yarn occurs before and after the air jet texturing.
 5. The method of claim 1, wherein the heating of the yarn includes heating the yarn to more than 90 degrees Celsius.
 6. The method of claim 1, wherein the heating of the yarn includes heating the yarn via a steam chamber.
 7. The method of claim 1, wherein the heating of the yarn is via one of a hot plate and a hot pin.
 8. The method of claim 1, wherein the heating of the yarn is via superheated steam.
 9. The method of claim 1, wherein the heating of the yarn includes passing the yarn through a treatment chamber.
 10. The method of claim 1, wherein the treatment chamber comprises: a flow-through steam chamber; and a closed nozzle.
 11. The method of claim 1, wherein the texturing of the yarn includes texturing the yarn via compressed air supplied at a pressure of more than about 8 bar.
 12. The method of claim 1, wherein the texturing of the yarn includes texturing the yarn via compressed air supplied at a pressure of more than about 10 bar.
 13. The method of claim 1, wherein the air reaches a speed of greater than about Mach 2 in the yarn channel.
 14. The method of claim 1, wherein the yarn exits the texturing nozzle at a speed greater than about 600 m/min.
 15. The method of claim 1, wherein the yarn exits the texturing nozzle at a speed greater than about 800 m/min.
 16. The method of claim 1, wherein the yarn exits the texturing nozzle at a speed greater than about 1500 m/min.
 17. The method of claim 1, wherein the conically shaped portion of the nozzle expands in a downstream direction.
 18. The method of claim 1, wherein the compressed air enters the yarn channel substantially at a central section of the channel.
 19. The method of claim 1, further comprising placing the yarn under tension after the yarn exits the air jet texturing nozzle.
 20. A device for treating a continuous filament yarn, the device comprising: a first feeder roll; a means for supplying drawn yarn to the first feeder roll; an air jet texturing nozzle defining a yarn channel having a conically shaped portion, the air jet texturing nozzle disposed downstream from the first feeder roll; a compressed air supply configured to radially enter the yarn channel substantially at an entrance of the conically shaped portion of the yarn channel such that the air reaches at least supersonic speed in the yarn channel; a second feeder roll disposed downstream from the air jet texturing nozzle; and at least one heating element disposed downstream from the first feeder roll and upstream from the second feeder roll.
 21. The device of claim 20, wherein the at least one heating element is disposed upstream from the air jet texturing nozzle.
 22. The device of claim 20, wherein the at least one heating element is disposed downstream from the air jet texturing nozzle.
 23. The device of claim 20, wherein the at least one heating element includes a first heating element disposed upstream from the air jet texturing nozzle and second heating element disposed downstream from the air jet texturing nozzle.
 24. The device of claim 20, wherein the heating element is chosen from one of hot pin and a hot plate.
 25. The device of claim 20, wherein the heating element includes a steam chamber.
 26. The device of claim 20, wherein the heating element is configured to heat the yarn to more than 90 degrees Celsius.
 27. The device of claim 20, wherein the air jet texturing nozzle is configured such that the compressed air reaches a speed greater than about Mach
 2. 28. The device of claim 20, wherein the device is configured such that the yarn has a speed greater than about 600 m/min as it travels through the texturing nozzle.
 29. The device of claim 20, wherein the device is configured such that the yarn has a speed greater than about 800 m/min as it travels through the texturing nozzle.
 30. The device of claim 20, wherein the device is configured such that the yarn has a speed greater than about 1500 m/min as it travels through the texturing nozzle.
 31. The device of claim 20, wherein the compressed air supply has a pressure of more than about 8 bar.
 32. The device of claim 20, wherein the compressed air supply has a pressure of more than about 10 bar.
 33. The device of claim 20, wherein the compressed air supply is configured to enter the yarn channel substantially at a central section of the yarn channel.
 34. The device of claim 20, wherein the second feeder roll is configured to place the yarn under tension as it exits the texturing nozzle.
 35. The device of claim 20, wherein the conically shaped portion of the yarn channel expands in a downstream direction. 